'use strict'

const fsp = require('fs').promises
const path = require('path')
const { DIRS, resolvePortablePath } = require('./paths')
const { newGame, newGameId, addGame } = require('./library')
const { extractIconFromExe } = require('./icons')

// Directories that typically hold installers/redistributables, not the game.
const SKIPPED_DIRS = new Set(['redist', 'directx', '_commonredist', 'support', 'dotnet', 'vc'])

function copyRecursive(src, dst, onProgress) {
  return fsp.readdir(src, { withFileTypes: true }).then(async entries => {
    await fsp.mkdir(dst, { recursive: true })
    for (const e of entries) {
      const s = path.join(src, e.name)
      const d = path.join(dst, e.name)
      if (e.isDirectory()) {
        await copyRecursive(s, d, onProgress)
      } else if (e.isFile()) {
        await fsp.copyFile(s, d)
        if (onProgress) onProgress(s)
      }
    }
  })
}

function moveFolder(src, dst, onProgress) {
  const fallback = () => copyRecursive(src, dst, onProgress).then(() => fsp.rm(src, { recursive: true, force: true }))
  if (path.parse(src).root !== path.parse(dst).root) return fallback()
  return fsp.rename(src, dst).catch(fallback)
}

async function importGame(srcDir, mode, onProgress) {
  const name = path.basename(srcDir)
  // Validate before touching the user's files: refuse an import without any
  // .exe (and don't half-move a folder we'd then have to roll back).
  const preExe = await findDefaultExe(srcDir)
  if (!preExe) return { ok: false, error: 'no-exe-found' }
  // The id doubles as the imported folder name, so generate it first and
  // create files/apps/<id> - no dedupe suffixes, ids can never collide.
  const id = newGameId()
  let workdir = srcDir
  if (mode === 'copy' || mode === 'move') {
    const dst = path.join(DIRS.APPS, id)
    if (mode === 'copy') await copyRecursive(srcDir, dst, onProgress)
    else await moveFolder(srcDir, dst, onProgress)
    workdir = dst
  }
  const exePath = (await findDefaultExe(workdir)) || preExe
  if (!exePath) {
    return { ok: false, error: 'no-exe-found' }
  }
  const game = newGame({ id, name, exePath, workdir, mode })
  game.imported = mode === 'copy' || mode === 'move'
  // the exe was picked automatically -> grab its icon right away; a missing
  // icon is not an import failure (game can still get one from config)
  const icon = path.join(DIRS.DATA, 'icons', id, 'icon.ico')
  if (extractIconFromExe(resolvePortablePath(exePath), icon).ok) {
    game.iconSource = icon
  }
  return addGame(game)
}

// Largest .exe in the tree, skipping redistributable folders. Files are
// stat'ed in parallel and folders walked breadth-first so big games don't
// turn the picker into a sequential crawl.
async function findDefaultExe(dir) {
  let best = ''
  let bestSize = -1
  const pending = []
  const consider = full => {
    const size = fsp.stat(full).then(st => st.size).catch(() => -1)
    pending.push(
      size.then(sz => {
        if (sz > bestSize) {
          best = full
          bestSize = sz
        }
      })
    )
  }
  const walk = async d => {
    let entries = []
    try {
      entries = await fsp.readdir(d, { withFileTypes: true })
    } catch {
      return
    }
    const subdirs = []
    for (const e of entries) {
      const full = path.join(d, e.name)
      if (e.isDirectory()) {
        if (!SKIPPED_DIRS.has(e.name.toLowerCase())) subdirs.push(full)
      } else if (e.name.toLowerCase().endsWith('.exe')) {
        consider(full)
      }
    }
    await Promise.all(subdirs.map(walk))
  }
  await walk(dir)
  await Promise.all(pending)
  return best
}

module.exports = { importGame, findDefaultExe, copyRecursive, moveFolder }